float a{1.f}; // 推荐花括号初始化,尽管c++98用不了 int b = reinterpret_cast<int&>(a); 可是reinterpret_cast并不会检查要重解释的类型的字节数是否一致啊之类的,还有大端小端的问题,一不小心就会ub(undefined behavior, 未定义行为) 因此c++又引入了更加安全的std::bit_cast (懒,不想写了) (第一...
编译器错误 C7591bit_cast 要求“%1$T”和“%2%T”大小相同 编译器错误 C7592“%1$T”类型的非类型模板参数至少需要“%2$M” 编译器错误 C7593返回类型要求不应是尾随返回类型“-> T”。 请考虑改用“-> std::convertible_to<T>” 编译器错误 C7594UTF-16 代理项“0x%x”无效 ...
在std::bit_cast 前,需要翻译对象表示为另一类型的对象表示时,能使用 std::memcpy: template <class To, class From> typename std::enable_if< (sizeof(To) == sizeof(From)) && std::is_trivially_copyable<From>::value && std::is_trivial<To>::value, // 此实现要求 To 可平凡默认构造 To...
当需要将对象的字节解释为不同类型的值时,可以使用std::memcpy或std::bit_cast(C++20 起): doubled =0.1; std::int64_t n; static_assert(sizeofn ==sizeofd);//n = *reinterpret_cast<std::int64_t*>(&d);//未定义行为std::memcpy(&n, &d,sizeofd);//OKn = std::bit_cast<std::int64_...
在一个表达式中,凡是可以使用int或unsigned int类型做右值的地方也都可以使用有符号或无符号的char型、short型和Bit-field。如果原始类型的取值范围都能用int型表示,则其类型被提升为int,如果原始类型的取值范围用int型表示不了,则提升为unsigned int型,这称为IntegerPromotion。做Integer Promotion只影响上述几种类型...
reinterpret_cast <new_type>(expression) 重解释转换 const_cast <new_type>(expression) 常量向非常量转换 总结 回到顶部(go to top) 隐式转换(implicit conversion) short a=2000; int b; b=a; short是两字节,int是四字节,由short型转成int型是宽化转换(bit位数增多),编译器没有warning,如下图所示。宽...
}; // as above int main() { // since C++11, use std::underlying_type to determine the underlying type of an enum typedef std::underlying_type< settings::flags> ::type flags_t; auto val = settings::bit1; switch (static_cast< flags_t> (val)) { case settings::bit0: break; ...
What is the alignment of a struct member with 64-bit pointers? What is the difference between _T and L? What is the difference between native api and win32 api? What is the difference of safe_cast, static_cast & dynamic_cast? What is the equivalent of C# #region in C++ what is thi...
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